Monitoring the impact of land cover change on surface urban heat island through google earth engine. Proposal of a global methodology, first applications and problems

All over the world, the rapid urbanization process is challenging the sustainable development of our cities. In 2015, the United Nation highlighted in Goal 11 of the SDGs (Sustainable Development Goals) the importance to "Make cities inclusive, safe, resilient and sustainable". In order to monitor progress regarding SDG 11, there is a need for proper indicators, representing different aspects of city conditions, obviously including the Land Cover (LC) changes and the urban climate with its most distinct feature, the Urban Heat Island (UHI). One of the aspects of UHI is the Surface Urban Heat Island (SUHI), which has been investigated through airborne and satellite remote sensing over many years. The purpose of this work is to show the present potential of Google Earth Engine (GEE) to process the huge and continuously increasing free satellite Earth Observation (EO) Big Data for long-term and wide spatio-temporal monitoring of SUHI and its connection with LC changes. A large-scale spatio-temporal procedure was implemented under GEE, also benefiting from the already established Climate Engine (CE) tool to extract the Land Surface Temperature (LST) from Landsat imagery and the simple indicator Detrended Rate Matrix was introduced to globally represent the net effect of LC changes on SUHI. The implemented procedure was successfully applied to six metropolitan areas in the U.S., and a general increasing of SUHI due to urban growth was clearly highlighted. As a matter of fact, GEE indeed allowed us to process more than 6000 Landsat images acquired over the period 1992-2011, performing a long-term and wide spatio-temporal study on SUHI vs. LC change monitoring. The present feasibility of the proposed procedure and the encouraging obtained results, although preliminary and requiring further investigations (calibration problems related to LST determination from Landsat imagery were evidenced), pave the way for a possible global service on SUHI monitoring, able to supply valuable indications to address an increasingly sustainable urban planning of our cities

Capacity of Urban Green Infrastructure Spaces to Ameliorate HeatWave Impacts in Mediterranean Compact Cities: Case Study of Granada (South-Eastern Spain)

Heat wave episodes are becoming more frequent and severe worldwide, especially in areas such as the Mediterranean region. This study is aimed at assessing the impact of heat waves in an urban environment and the ways areas of urban green infrastructure (UGI) can play key roles in moderating the impacts of these high-temperature events. We analyzed land surface temperature (LST) and normalized difference vegetation index (NDVI) data retrieved from Landsat 8/9 satellite images. These data were recorded during heat wave episodes from 2017 to 2022 in a representative Mediterranean medium-sized compact city. We carried out a correlation analysis between LST and NDVI per area type and as individual units to assess how UGI elements can contribute to the cooling of the urban matrix during heat wave episodes. Those small green spaces distributed throughout the city, defined as “Other” areas, showed stronger negative correlation. These spaces are particularly relevant for Mediterranean cities, where highly limited space in city centers hinders the possibility of having larger-surface UGI elements. The study highlights the need for further research into the composition of those small public green spaces to understand how their components enhance the city’s cooling capacity given the climate conditions and water scarcity in the Mediterranean regionPre-competitive Research Projects University of Granada Own PlanProject PP2022.PP.34Pre-GREENMITIGATION

The Challenge of the Urban Compact Form: Three-Dimensional Index Construction and Urban Land Surface Temperature Impacts

Cities are growing higher and denser, and understanding and constructing the compact city form is of great importance to optimize sustainable urbanization. The two-dimensional (2D) urban compact form has been widely studied by previous researchers, while the driving mechanism of three-dimensional (3D) compact morphology, which reflects the reality of the urban environment has seldom been developed. In this study, land surface temperature (LST) was retrieved by using the mono-window algorithm method based on Landsat 8 images of Xiamen in South China, which were acquired respectively on 14 April, 15 August, 2 October, and 21 December in 2017, and 11 March in 2018. We then aimed to explore the driving mechanism of the 3D compact form on the urban heat environment (UHE) based on our developed 3D Compactness Index (VCI) and remote sensing, as well as Geo-Detector techniques. The results show that the 3D compact form can positively effect UHE better than individual urban form construction elements, as can the combination of the 2D compact form with building height. Individually, building density had a greater effect on UHE than that of building height. At the same time, an integration of building density and height showed an enhanced inter-effect on UHE. Moreover, we explore the temporal and spatial UHE heterogeneity with regards to 3D compact form across different seasons. We also investigate the UHE impacts discrepancy caused by different 3D compactness categories. This shows that increasing the 3D compactness of an urban community from 0.016 to 0.323 would increase the heat accumulation, which was, in terms of satellite derived LST, by 1.35 °C, suggesting that higher compact forms strengthen UHE. This study highlights the challenge of the urban 3D compact form in respect of its UHE impact. The related evaluation in this study would help shed light on urban form optimization

Modeling the Surface Urban Heat Island (SUHI) to study of its relationship with variations in the thermal field and with the indices of land use in the metropolitan area of Granada (Spain)

Understanding just how the increase in the Earth’s Surface Temperature (LST) is related to alterations of the urban climate —Surface Urban Heat Island (SUHI) or Urban Hotspots (UHS)— and with the deterioration of cities´environmental quality has become a great challenge. Societies worldwide seek actions that might break these trends and improve the quality of life of local inhabitants. In this research, with the help of Landsat 5, 7 and 8 satellite images, the evolution of land use/cover (LULC), LST and SUHI were studied over a long period, from 1985 to 2020, in the metropolitan area of the city of Granada (Spain). The aim was to evaluate how these variables, together with the Urban Index (UI), Normalized Difference Built-up Index (NDBI), Normalized Difference Vegetation Index (NDVI) and Proportion of Vegetation (PV), have influenced the variability of the UHS and the level of thermal comfort according to the Urban Thermal Field Variance Index (UTFVI). Reported as results, corroborated by statistical analysis, are mean increases in LST (2.2◦C), SUHI (0.6◦C), UHS (20.4%), and class 6 of the UTFV (26.2%). NDBI and UI are associated with high variations in LULCs. These have suffered increases in built-up and bare soil coverage, and decreases in water bodies, vegetation and farmland coverage

A Review on Different Modeling Techniques

In this study, the importance of air temperature from different aspects (e.g., human and plant health, ecological and environmental processes, urban planning, and modelling) is presented in detail, and the major factors affecting air temperature in urban areas are introduced. Given the importance of air temperature, and the necessity of developing high-resolution spatio- temporal air-temperature maps, this paper categorizes the existing approaches for air temperature estimation into three categories (interpolation, regression and simulation approaches) and reviews them. This paper focuses on high-resolution air temperature mapping in urban areas, which is difficult due to strong spatio-temporal variations. Different air temperature mapping approaches have been applied to an urban area (Berlin, Germany) and the results are presented and discussed. This review paper presents the advantages, limitations and shortcomings of each approach in its original form. In addition, the feasibility of utilizing each approach for air temperature modelling in urban areas was investigated. Studies into the elimination of the limitations and shortcomings of each approach are presented, and the potential of developed techniques to address each limitation is discussed. Based upon previous studies and developments, the interpolation, regression and coupled simulation techniques show potential for spatio-temporal modelling of air temperature in urban areas. However, some of the shortcomings and limitations for development of high-resolution spatio- temporal maps in urban areas have not been properly addressed yet. Hence, some further studies into the elimination of remaining limitations, and improvement of current approaches to high-resolution spatio-temporal mapping of air temperature, are introduced as future research opportunities

Exploring Urban Spaces across Human-Natural systems and the Potential to Enhance City Resilience

In dieser Dissertation werden vier Studien durchgeführt, um die acht Arten von Räumen in Mensch-Natur-Systemen für die Widerstandsfähigkeit von Städten vorzuschlagen, die Verbesserung von städtischen Grünflächen unter qualitativen und quantitativen Gesichtspunkten zu analysieren, die Beziehung zwischen UGSLandschaftsmerkmalen und menschlichen Emotionen zu bestimmen und das Konzept der selbstlernenden Stadt für die städtische Raumplanung zu veranschaulichen. (1). Unterschiedliche Strategien in den Acht-Typen-Räumen in Mensch-Natur-Systemen. (2). Verbesserung der städtischen Grünflächen mit natürlichem Angebot und menschlicher Nachfrage. (3). Das Konzept der selbstlernenden Stadt für urbane Nachhaltigkeit. (4) Für die städtische Nachhaltigkeit erfordert die Planung eine Neubewertung der Verbindungen zwischen den verschiedenen menschlichen und natürlichen Systemen mit den Wechselwirkungen zwischen Bedarf und Versorgung Städtische Räume sind komplex, weisen aber in verschiedenen Methoden und Konzepten Regelmäßigkeiten auf. Für eine nachhaltige Entwicklung in Städten sind kreative Denkansätze für die Umsetzung und Integration von sich überschneidenden Räumen, Elementen und Kulturen in städtischen Mensch-Natur-Systemen erforderlich. Um eine nachhaltige Stadt zu schaffen, sind urbane Räume unerlässlich.This dissertation conducts four studies to propose the eight-type spaces in human-natural systems for city resilience, to analyze the improvement of urban green spaces from quality and quantity perspectives, to determine the relationship between UGS landscape characteristics and human emotions and to illustrate the concept of city self-learning for urban space planning. (1). Different strategies in the eight-type spaces across human-natural systems. (2). Improving urban green spaces with natural supply and human demand. (3). The concept of city self-learning for urban sustainability. (4) For urban sustainability, planning requires reevaluating the connections between different human-natural systems with the interactions of demands and supplies. Dissertation title: Exploring Urban Spaces across Human-Natural systems And the Potential to Enhance City Resilience Urban spaces are complex but have regularity in several methods and concepts. For sustainable development in cities, creative ways to think about implementations and integrations utilize crossing spaces, elements, and cultures in urban human-natural systems. To make a sustainable city, urban spaces are essential

Characterizing the relationship between land use land cover change and land surface temperature

Exploring changes in land use land cover (LULC) to understand the urban heat island (UHI) effect is valuable for both communities and local governments in cities in developing countries, where urbanization and industrialization often take place rapidly but where coherent planning and control policies have not been applied. This work aims at determining and analyzing the relationship between LULC change and land surface temperature (LST) patterns in the context of urbanization. We first explore the relationship between LST and vegetation, man-made features, and cropland using normalized vegetation, and built-up indices within each LULC type. Afterwards, we assess the impacts of LULC change and urbanization in UHI using hot spot analysis (Getis-Ord Gi∗ statistics) and urban landscape analysis. Finally, we propose a model applying non-parametric regression to estimate future urban climate patterns using predicted land cover and land use change. Results from this work provide an effective methodology for UHI characterization, showing that (a) LST depends on a nonlinear way of LULC types; (b) hotspot analysis using Getis Ord Gi∗ statistics allows to analyze the LST pattern change through time; (c) UHI is influenced by both urban landscape and urban development type; (d) LST pattern forecast and UHI effect examination can be done by the proposed model using nonlinear regression and simulated LULC change scenarios. We chose an inner city area of Hanoi as a case-study, a small and flat plain area where LULC change is significant due to urbanization and industrialization. The methodology presented in this paper can be broadly applied in other cities which exhibit a similar dynamic growth. Our findings can represent an useful tool for policy makers and the community awareness by providing a scientific basis for sustainable urban planning and management.First, the authors would like to thank the European Commission and the Erasmus Mundus Consortium for providing the master scholarship in Geospatial Technologies. We acknowledge the USGS-NASA due to their freely accessible Landsat data. Thanks are also due to the Laboratory for Geographic Information Analysis (Department of Geography, Hanoi National University of Education) for providing valuable tools and software. This work has also been partially supported by the Spanish Ministry of Economy under project ESP2013-48458-C4-3- P

Earth Observations for Addressing Global Challenges

"Earth Observations for Addressing Global Challenges" presents the results of cutting-edge research related to innovative techniques and approaches based on satellite remote sensing data, the acquisition of earth observations, and their applications in the contemporary practice of sustainable development. Addressing the urgent tasks of adaptation to climate change is one of the biggest global challenges for humanity. As His Excellency António Guterres, Secretary-General of the United Nations, said, "Climate change is the defining issue of our time—and we are at a defining moment. We face a direct existential threat." For many years, scientists from around the world have been conducting research on earth observations collecting vital data about the state of the earth environment. Evidence of the rapidly changing climate is alarming: according to the World Meteorological Organization, the past two decades included 18 of the warmest years since 1850, when records began. Thus, Group on Earth Observations (GEO) has launched initiatives across multiple societal benefit areas (agriculture, biodiversity, climate, disasters, ecosystems, energy, health, water, and weather), such as the Global Forest Observations Initiative, the GEO Carbon and GHG Initiative, the GEO Biodiversity Observation Network, and the GEO Blue Planet, among others. The results of research that addressed strategic priorities of these important initiatives are presented in the monograph